Intermittent film-advancing mechanism



Sept. 13, 1949. o. wlTTE-L 2,481,706

INTERMITTENT FILM- ADVANC I NG MECHANI SM Filed March 20, 1948 O 'IITO W1 TTEL INVENTOR WJW BY E

' ATTORNEEVZ" Patented Sept. 13, 1949 INTERMITTENT FILM-ADVANCING MECHANISM Otto Wittel, Rochester, N. Y., assignor to East,- man Kodak Company, Rochester, N. Y., a corporation of New Jersey Application March 20, 1948, Serial No. 16,083

. 1 I This invention relates to photography and particularly to a film-advancing means for intermittently feeding a perforated motion picture film past an exposure aperture in a cinematographic apparatus. 7

Two generally different types of intermittent claw pull-down mechanisms have been used in the pastin cinematographic apparatus. One of these is the 'claw pull-down mechanism of the ratchet type wherein the claw is reciprocated by an eccentric member and is normally forced into the film path by a spring and the claw tip ratchets out of the engaged perforation and along the perforated edge of the film during the upstroke. The other type is where the up-and-down and in-and-out movement of the claw is controlled by separate cooperating cams and follower surfaces. e

The ratchet type pull-down claw" mechanism possesses the advantages of mechanical simplicity and being, inexpensive, but has the disadvantages that it is hard on the film and it is difficult to keep the clawin engagement with the film perforation during the pull-down stroke without there being a sawing faction occur between the claw and the engaged perforation edge. From the operational standpoint, the pull-down mechanisms using two separate cams for producing the pull-down stroke and the inand-out movements of the claw are better than the ratchet type claw mechanisms: However, from the mechanical standpoint, they are much more expensive and difficult to keep in operation because of the critical synchronism required between the rotation of the cams that isnecessary and because of the exacting nature of the cam surfaces to produce the'required motions. V

The primary object of the present invention is to provide an intermittent claw-advancing mechanism which has the advantages of the ratchettype claw mechanisms and the dual cam -type claw feeds, but none of the disadvantages characteristic of each. j I

Another object is to provide an intermittent claw film-feeding mechanism which includes a clawreciprocated by an eccentric to obtain the required up-anddown stroke and which includes two stationary guiding surfaces engaged by two separate follower surfaces on the clawmember to control the in-and-out movement of the claw rela- 8 Claims. (01. se -1'84) held-retracted during the return stroke of the claw and is allowed to enter a film perforation at the beginning of the pull-down stroke and is held in engagement with the perforation throughout the pull-down stroke without a sawing 'action occurring between the claw and the engaged edge of the film perforation, all without benefit of a single driven cam. And, another object is to provide. a claw-type film-advancing mechanism which is extremely simple in construction while at the same time being very efficient in operation. I v

The novelfeatures that I consider characteristic of my'invention are set'forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanyingdrawings, in which Fig.1 is an enlarged fragmentary side elevation of the front end of a motion picture camera, partly in section, showing a pull-down mechanism constructed in accordance with a preferred embodiment of. the present invention and with the parts shownin the positions they assume when the claw has just started its return stroke after havingadvanced the film one frame; 7 f

Fig. 2 is a fragmentary side elevation of the claw mechanism showing the parts in the position they assume just after the claw has started'its pull-down stroke; r

Fig. 3 is an enlargement of that portion of Fig. 2 including the-claw end of the claw member and the parts engaged thereby to bring out the details of these parts and their engagement with more cler tm :5- 1.. Fig. 4 is an elevational view looking at the film gate from the rear and with the movable gate member removed Fig. 5,is an enlarged perspective detail showing the spring for forcing the claw toward the gate and showing the fingers for guiding the claw member laterally of the film gate; 1

Fig. 6 is a sectional detail taken through the eccentric mounting for the claw member and showinghow the length of the claw stroke can be varied; and

Fig. 7 is a diagrammatic view illustrating the path of the tip of the film claw during one com-. plete stroke of the claw member. 7 Likereference characters refer to corresponding parts throughout the drawings.

1 I Referring now to thedrawingsand particularly Figs. 1 and 4, the present pull-down mechanism is adapted for advancing a motion picture film F through the gate ID of a motion picture camera and across an exposure aperture I I which is optically aligned with the camera objective, not shown. The shutter, not shown, for intermittently-cutitingoff the light entering the objective, as is weir known, is adapted to be mounted in a shutter housing I2 mounted at the front of the camera and fixed to the mechanism plate within the camera body, not shown.

Film gate comprises an aperture plate I3 pin 32 to the bracket '30 against which the forfixed to the rear of the shutter housing l2 by screws [4. As clearly shown in Fig. 4, thisaperture plate has its center portion l5 efrset'froin a pair of rails 16 which engage the perforated of that portion of the aperture platetraversed by the claw. As a result, the claw maintains'the teristic; of some existing Ip'ull-dov l'r if mecl'ianisms.

Just assoon as 'the claw 'r'nemb'er starts its up or return stroke, it is desirable to positively retract the claw from the engaged film perforation and to hold it. retracted throughoutthe return stroke of the claw. To this end, I fix a guide fi war djedg of'the c'law member is forced the instaht theicllaw'istarts its upstroke. That portion of the forward edge of the claw member margins of the film and prevent the picture area of the film from rubbing on the gate member. One of the rails is provided with a recess "l1 into which the tip of the claw may extend during the pull-down stroke. As clearly shownin Fig. '1, theJower end ofthe gate, or that portion'below th exposure aperture, is curved forwardly of the *qptifcal axis. The film i's'held fiat against the rails 16 of the aperture plate l3 by 'arear gate member lfi'which is normally spring-pressed 'thereagainst by'a' spring l9, as is commonpractice. This rear gate member conforms in shape iandisiz'jefto'the aperture plateand has a cut out portion," not shown, which allowsthe claw to pass therethro'ugh to engage the film strip.

The pu1l-down"claw mechanism which is adapted to intermittently advance the film strip from a 'supply'loop, not shown, in advance of the jgatepas't the exposure aperture H and thence to asupply loop,.not" shown, beyond the gate will how bedescribed. Below and to one side of the gatejis located a driving disk 20 fixed to a shaft 2lfwhich is, connected to a spring motor, not shown. As illustrated, this disk is to bedriven clockwise. Rotatably mounted on a pin 22 car'- this diskeccentrically ofits center is a clawmember 23 which is reciprocated llD-and= down asthe disk' rotates. The upper end of the cl'awlmember is bent at right anglesto the main body of the memberyas shown at 24 in Fig-4i and on-the end of this turned over portion of the claw member, which extends transversely of the gate, there is a claw 25; which is 'adapted'to ex tend into a film perforation during the pull do'wn strokejto advance the film.

" The claw is normally forced toward'the film path by a spring finger 26 engaging the rear edge of the claw member and which'spring finger is formed up'from a clip 27 mounted on the rear end 'ofthe shutter housing by screws, as indicated at 28 in Fig: '4. The'depthof penetration of the claw into thefilm perforations, or across the'ifi lni path, is controlled by a straight guiding surface 29 011 the" edge of-a part of 'abracket -39" fixed to the shutter housing by screws 3|. This guid ing surface 2-9 isengaged by the bent-over portion 24'' of the claw member and is accurately finished and hardened because the part2! of the claw member slides along this surface during the pull-downstroke of the claw. Althoughthis guiding 'surface'is straight and is substantially parallel to a'tangent to the curved portion or the gate. because of the oscillating action of the eccentrically mounted end ofythe claw member during the pull-down portion of its cycle; along with the sliding fulcrum action of the portion '24 of the claw member on guiding surface'2-9, the tip of theclaw inscribesaeurvea line path duce friction bet-we merit-in the stroke of the claw;-

. are carried we sati "adapted to engage said guide pin is provided with a cam surface 33 which, when moved over the' guide pin, will cause the claw to be retracted from the engaged film' perforation and remain retracted r g theii bstrol ie of th'clawr" '(See Fig. 7.) j Itj will be noticed that when t e-tam surfacejii is engagi'n'gthe guide-pinch th stroke of the" new, the bentover 'portioii i of the claw member is spacedirom and-does not engage the guidiflgi surfaic 9. Ori'tl'ie other hand, during the pull-down troke' wheh'the poi; mama of'the claw 'merhberis riaing; irtlieg "a: ingsurface 29 the cam surface3 3 isheld 1e' of th'e'guidefpin 3'I.

'As shown 'in enlarge in Fig. 7, the tip' orth v atthe'e'nd of thepull -down-stiokejustasi rts on the upstroke. "-Howevenfduringthis h and without its upper edge hittirig the up A of the per'foratiomarid thu's'ter'idingto rev" se the direction of y the film becausethe film-en'g g= ingendof the claw 'is' tapered to-aiioirf and is capableotasubstahtial'rriovmn *re'la we to the film. perforation. 4 re re u e friction etween the fspring finger;zii ar'rd thejf'r'ear edge jof the claw to a'm mmgm" "the spring finger? is bo' away from the cl empeeas shown; :T will be a minimuhfiof fric on betw'en'th be toverportion 2'4 oft-he claw member-and gum:

surface 219 because, asfshown 'in Fig 3 0E119 li' i r r t ii i rf q. 24 win h r engages, the g umg-sm'rmze during thei'riai'ii' portion prthe pull dowfn stroke. j 3 'I'he claw member 23 isguided later Q film gate by pair of spaced fin ers- 4o tea '4 which engage'oppo'sit faces tit-the claw me as clearly shown in Figs 4fand 5. "These fi'ng is? 'Fwhi'c'h isrneunt the guide pin*32 answmeh-immae over end 42 engaging of the bracket 2' 0 to p turning on the guide ilfli of thejc law me e'r, e fingers may 7 away from tneengagea faces of theber, as shown. I A *"I-Of allow a herself-ferment of f" to the claw on the eccentric of t e wees twar": Fig. 6 may be used. A5shownintri-isfigeregtn c1 aw men-fiber 2 3 'e 1'='ieli-rc-ilesar'-1-- 'ci-itij-ic' s'houli'f ont-he bearing 45 which isQ- -inturn; rotatably mounted on the pin-unseat claw member is frictionally held a thebearmg 45 between awasher' w staked if (see Fig.- 7) which corresponds to the curvature the pin ZZ-Bya washer aria screw-'"coiiibiriafifi.

th e wt; was 1 h 'beari-ng 48, the 1' screw-1 engaging a tapp'edbore in" the. pin 22- The flange 41 f .the :bearing is'. provided with a pair 0f" diametrically i opposite slots to receive aspanner wrench byjthe useof which .the bearing may be turned relative to the claw member if the-latter is held against rotationi The length of stroke of the claw: can thus be shifted overa'range 'edual'to the *e'ccentricity of the shoulder of the bearing 45 engaged by'the claw membeIgJ-Ln" .41. 1p

:It'will thus be seen'that I have provided a claw pull-down mechanism which has the mechanical simplicity of. one of the ratchet type :but .which provides for the positive retraction of'the claw from engagement with the film during the return or upstroke. The desired in-and-out movement ofthe' clawrelative to the film'path is accomplished without the use of driving-scams which require-synchronous operation. Throughout the pull-down stroke the claw maintains a fixed penetration relative to the engaged film perforation so that there is no sawing actionbetween the film-engaging edge of the claw and the edge of the engaged perforation to damage the film or upset the-amount and smoothness of the film nc d- .1; I

AlthoughI have shown and, described certain specific embodiments ofmy invention, I amfully aware that many modifications thereof are possible. My invention therefore is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United States is:

1. A film-advancing assembly for intermittently feeding a perforated film strip through a path defined by a guideway and comprising the combination with a claw member having a claw on one end thereof for intermittently engaging successive perforations of said film strip and including an eccentric member for reciprocating said claw member through a pull-down stroke, of means for causing said claw to engage a film perforation at the beginning and during said pulldown stroke and for retracting said claw from the engaged perforation at the end of the pulldown stroke and maintaining it retracted throughout the return stroke of said claw, said means including means for normally forcing said claw member toward the guideway, a pair of stationary guiding surfaces disposed adjacent said guideway and spaced from one another length- Wise thereof, and a pair of follower surfaces on said claw member and spaced lengthwise thereof, one of said follower surfaces adapted to engage one of said guide surfaces during movement of the claw member in one direction and the other follower surface adapted to engage the other guiding surface during movement of the claw member in the other direction for controlling the position of the claw relative to the film path.

2. The combination according to claim 1, in which that portion of the film path traversed by the claw is curved away from the claw member, one of said guiding surfaces is straight, and substantially parallel to a tangent to the curved portion of the film path and is as long as the pulldown stroke of said claw member, and the follower surface on the claw member adapted to engage this guiding surface is at the free end of the claw member adjacent the claw and is adapted to engage this surface during the pull-down stroke, whereby the combined action of the eccentric member on the claw member and the sliding engagement between said guiding surface and the freeend of-the clawcauses the film-engaging end of theclaw to move-inacurved path corresponding toathatzofthe curved. portion of the film path; l- 1. e V

-3. gA-film-advancing, assembly for ,intermittente lyfeeding a perforated ,filmfstr'ip through a path defined by a guideway; and 1 comprising .;the combination with aclaw member, having claw on one end thereof for intermittently ien-, gaging successive .:perforations of said film. strip and including an eccentric member connected to the other endof th'eclawmember for recipro-v cating said claw/member through a pulldown' stroke, of means for causing said claw to engage a film perforation -':during its pull-downvstroke and for retracting said claw from; the film perforation at; the" beginning .of the return stroke and maintaining it retracted throughout the: re=-' turn stroke, said last-mentioned meansincluding means normally forcing said clawmember toward the filmpath; a guiding surfacefladjacent the guideway and extending the l'ength of the pull down stroke adapted to be engaged by a; portion on said clawunember, adjacent said claw during the, pull-down stroke to control the extent :of penetration of. the clawinto the Zfilm path, a fixed guidepin disposed adjacent saidguideway and intermediate the ends'iof saidclaw. member, and the edge of said claw member provided with a cam surface extending lengthwise thereof and including a portion which is adapted to engage said guide pin at the end of the pull-down stroke and during the return stroke thereof to retract and hold the claw out of the film path.

4. The combination according to claim 3 in which said guiding surface is on the end of a plate located to one side of said guideway and extending to the rear thereof, the main body of the claw member and the eccentric member for driving the same lie in planes to one side of the guideway and said claw is connected to the main body of said claw member by an arm extending substantially at right angles to the body of the claw member'and transversely of said guideway and guiding surface, whereby said arm is adapted to engage and ride on said guiding surface during the pull-down stroke of said claw to control the depth of penetration of said claw into the film perforations.

5. A film-advancing assembly for intermittently feeding a perforated film strip through a path defined by a stationary guideway and comprising the combination with a claw member having a claw on one end thereof for intermittently engaging successive perforations of said film strip and including an eccentric member connected to its other end for reciprocating said claw member through a pull-down stroke, of means for causing said claw to engage a film perforation at the beginning and during said pulldown stroke and for retracting said claw from the engaged film perforation at the end of the pull-down stroke and maintaining it retracted throughout the return stroke of the claw, said means including a bracket fixed to the guideway and including a portion disposed to one side of and extending rearwardly of the film path and terminating in a guiding edge extending longitudinally of the film path, a spring normally acting on the claw member to force the claw end thereof toward the guideway, a follower on the claw member adjacent the claw bearing end thereof adapted to engage said guiding edge during the pull-down stroke to control the depth of which the 'sprirlg'rnormally acting on the rel-aw member re fierce th-e :c'l'vlr :end thereof toward the film path comfiri'ses' aleaf spring fixed to the member *saii-l, sprihg being bowed away from said claw 'inelnber to reduce the .frietibnal cbnta'ct between the two part. i Y

7 7. The ebmbinatlon 'ac'brcli-ng to' claim 5 and including means fbr'ui'di'rlg the claw :rnenfla-er transversely of said guidewy, said .last=h1'ehtieneil mean comprising a, support member pivt e'd on said braeket anii ihclud-irlg a pair e'f spaed fingers adapted to en' gageU'ppos-ite Iac'es of said claw member; a pnrfiibn bf said support mefime'r extending substantially at right 'a'hg-l'es t'o said s notch-{in of skidbrabket'to preveht'mhe 'suppqf from piv? otlng ofi Said. bra'cketin response te :frietiohial force's between'the jepaeed-flnagers'end the claw I member.. 1

"a. Tnexeembimfie eceording e0 elem 1 :5 n"

the clawglszeurved away fromfohe claw member;

said guiding edge is straig'ht .a'n-d 'sfibstantially parallel to a tangent to the curved portionief-sai-d. film path, and thee'ceeritric member is,;bel'ow and slightly lierwalfd emne .pdrtiohnf the guide;

WaJy' traversed by said claw, whereby mevemem of the lewer end 0f the claw member flurlng the pulP-dowil stroke setfi up a Ifulcru-m action tween said guiding edge and the follovlfer son-(she claw member which cail'ses said claw to :follfi'w :a curve corresponding to that of 'the filihlpathaj Number 7 Name 2,076,189 Witt-X21 2,346,070 Feller A; 

